Hmmmm. What can I say, I love Brave Halfling products and I LOVE Labyrinth Lord but Old School was NEVER this basic.
What we have here is some rooms with some monsters and some treasure. It's all brawn and no brain. If you don't like one samey combat after another, this won't be for you. In fact, the more I think about it, the more this module feels like a 4E "adventure" converted to LL.
The Mountain King himself is kinda OK but he's just stats on the page. This adventure lacks atmosphere and a sense of purpose.
The potential of this product comes from what the referee is prepared to add and there's room to add. Too much room.